Multiple CMT source analysis of the 2004 Sumatra earthquake
While it is agreed that the great Sumatra earthquake of December 26, 2004 was among the largest earthquakes of the past century, there has been disagreement on how large it was, which part of the fault ruptured, and how the rupture took place. We present a centroid-moment-tensor (CMT) analysis of the earthquake in which multiple point sources are used in the inversion to mimic a propagating slip pulse. The final model consists of five point sources, with the southernmost sources accounting for the majority of the moment release. The presumed fault planes of the southern sources strike northwest, while those in the north strike northeast, consistent with the geometry of the subduction trench. Slip on the fault is found to be more oblique in the north than in the south. The inversion with five sources leads to a moment magnitude for the Sumatra earthquake of M_W = 9.3, consistent with estimates from long-period normal-mode amplitudes.
Additional Information© 2005 by the American Geophysical Union. Received 14 June 2005; revised 27 July 2005; accepted 10 August 2005; published 9 September 2005. We thank H. Kanamori, C. Ammon, M. Antolik, R. Bürgmann, M. Ishii, T. Lay and two anonymous reviewers for helpful comments. The GSN data analyzed were collected and distributed by the Incorporated Research Institutions for Seismology (IRIS) and the USGS. This research was supported by a Harvard University James Mills Peirce Fellowship and a National Science Foundation (NSF) Graduate Research Fellowship (VCT) and by NSF grant EAR-0207608.
Published - Tsai_etal_GRL2005.pdf
Supplemental Material - grl20327-sup-0001-t01.txt
Supplemental Material - grl20327-sup-0002-t02.txt